Microplastics: Antidote or Trojan Horse of Copper Ion Toxicity in Submerged Macrophytes

Chinese Academy of Sciences

Microplastics (MPs) are plastic particles with size less than five mm that can absorb other contaminants (i.e., heavy metals) and influence their toxicity and fate in aquatic ecosystems due to their unique surface structure and physicochemical properties. Research on combined effects of MPS and other contaminants on organisms is limited and the conclusions remain controversial.

Researchers from the Wuhan Botanical Garden of the Chinese Academy of Sciences, together with collaborators from Wuhan University, have addressed this research gap by investigating the adsorption behavior of copper ions (Cu2+) on different-sized polyethylene (PE) (five and 150 μm) and their combined effects on four submerged macrophytes species. Adsorption tests, batch experiments on combined effect of MPs and Cu2+ were conducted.

According to the researchers, the addition of PE has reduced Cu2+ concentrations in the mixed solution. Both the initial Cu2+ and MPs concentrations affected the adsorption amounts of Cu2+ in MPs. PE alone did not exhibit inhibitory effects on macrophytes, while Cu2+ showed fatal toxicity.

In addition, the combination of PE and Cu2+ reduced the toxicity of Cu2+ to macrophyte and the toxicity attenuation varied among species. Furthermore, PE could transport Cu2+ between different systems and therefore transfer Cu2+ toxicity on macrophytes in the imported system.

This study indicates that MPs reduces the toxicity of other contaminants through adsorption as an antidote, and introduces external pollutants into new environments through desorption as a carrier.

This work was supported by the National Natural Science Foundation of China. Results have been published on Water Research entitled “Antidote or Trojan horse for submerged macrophytes: Role of microplastics in copper toxicity in aquatic environments.”

Antidote or Trojan horse for submerged macrophytes: Role of microplastics in copper toxicity in aquatic environments. (Image by WBG)

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